In Austrian Pat. No. 286,072 there is described a portable gas appliance in the form of a torch-heated propane gas soldering iron with an igniter which produces a torch-like flame at the mouth of a burner, this flame being trained upon the soldering iron head to heat the latter to a temperature at least sufficient to melt solder.
The flame is generated by a tubular burner mouth ahead of which is provided a mixing nozzle supplied with the propane gas by a feed tube. A spark wheel igniter is used to produce the spark which ignites the gas mixture to form the flame.
This igniter fires a branched stream of the gas mixture which, in turn, causes the ignition of the main stream. The ignition thus occurs upstream of the nozzle.
Experience with this type of ignition system has shown that it is relatively expensive to fabricate and is not always completely reliable or satisfactory.